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how is a gear tooth vernier gage used???

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  • how is a gear tooth vernier gage used???

    i'm not really thinking of bidding on this (and it will go for $250 now that i posted it here), but how the heck do you use one of these things?????

    http://cgi.ebay.com/ws/eBayISAPI.dll...502086901&rd=1

    andy b.
    The danger is not that computers will come to think like men - but that men will come to think like computers. - some guy on another forum not dedicated to machining

  • #2
    Using a gear tooth vernier caliper is easy enough. Set the gear's chordal addendum on the addendum vernier (works on the blade thingy) and straddle the gear tooth with the caliper. Bring the jaws together a tiny bit at a time till no free motion is felt when you wiggle the beam a trifle.

    You use it to measure gear teeth, coarser screw threads (expecially Acme and square threads), thicknesses of bevels, etc.

    Don't forget the mystery words "chordal addendum". That's the height from the pitchline to the tip of the gear tooth. The "chordal" comes in because you have to calculate the chordal height of the little arc subtended by the gear tooth at the pitchline and add it to the addendum. There's some discussion, a formula, and some tables in "Machinery's Handbook".

    [This message has been edited by Forrest Addy (edited 03-20-2005).]

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    • #3
      Andy_b----

      There was an article some time back in HSM or MW on a simple adapter for a ordinary caliper to mimic this tool. You are right these go for stupid money! LK

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      • #4
        I have a book which gives a good formula for measuring across a few teeth at a time, all you need is a micrometer with disc type anvils to get between the teeth, much cheaper than a gear tooth vernier.
        Also be aware that the vernier is not good at measuring fine pitch gears, it is just too bulky, so if you are into the smaller stuff, forget it.
        Phil

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        • #5
          When you really get bit by the gear bug you NEED one of these



          Ideal for geriatric gear heads with lens's like coke bottle bottoms.

          John S.

          BTW. I always thought a Geriatric was a German fast bowler?
          .

          Sir John , Earl of Bligeport & Sudspumpwater. MBE [ Motor Bike Engineer ] Nottingham England.



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          • #6
            One word of warning about Gear Tooth Verniers. They have a 20 division vernier scale insteadof 25. Found out the hard way
            Forty plus years and I still have ten toes, ten fingers and both eyes. I must be doing something right.

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            • #7
              This link may be useful http://www.omnigearandmachine.com/ge...h_verniers.htm

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              • #8
                Forrest,

                you just blew my mind.


                John S.,

                i wouldn't even want to guess at what that contraption costs.


                All,

                i need to find me a book on gears and figure this out.


                andy b.
                The danger is not that computers will come to think like men - but that men will come to think like computers. - some guy on another forum not dedicated to machining

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